Allow certain SP recorder classes to defer their "begin" operation.

Source/platform/graphics/paint/DrawingRecorder.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef DrawingRecorder_h
 #define DrawingRecorder_h
 
 #include "platform/PlatformExport.h"
 
 #include "platform/geometry/FloatRect.h"
 #include "platform/graphics/paint/DisplayItem.h"
 
 #ifndef NDEBUG
 #include "wtf/text/WTFString.h"
 #endif
 
 namespace blink {
 
 class GraphicsContext;
 
 class PLATFORM_EXPORT DrawingRecorder {
 public:
+    DrawingRecorder(GraphicsContext&, const DisplayItemClientWrapper&, DisplayItem::Type);
     DrawingRecorder(GraphicsContext&, const DisplayItemClientWrapper&, DisplayItem::Type, const FloatRect& cullRect);
     ~DrawingRecorder();
 
+    void begin(const FloatRect& cullRect);
+
     bool canUseCachedDrawing() const
     {
 #if ENABLE(ASSERT)
         m_checkedCachedDrawing = true;
 #endif
         return m_canUseCachedDrawing;
     }
 
 #if ENABLE(ASSERT)
     void setSkipUnderInvalidationChecking() { m_skipUnderInvalidationChecking = true; }
 #endif
 
 private:
     GraphicsContext& m_context;
     DisplayItemClientWrapper m_displayItemClient;
     const DisplayItem::Type m_displayItemType;
     bool m_canUseCachedDrawing;
+    bool m_engaged;
 #if ENABLE(ASSERT)
     mutable bool m_checkedCachedDrawing;
     size_t m_displayItemPosition;
     bool m_skipUnderInvalidationChecking;
 #endif
 };
 
 } // namespace blink
 
 #endif // DrawingRecorder_h